Creamy Potato Gratin Thyme

I was standing at my kitchen counter on a rainy Thursday evening, half-listening to an old French cooking show on the radio, when I realized I had nothing planned for dinner except a bag of potatoes and some cream about to expire. That gratin turned into one of those dishes I now make without thinking, the kind that fills the house with warmth before anyone even takes a bite.

The first time I brought this to a potluck, my friend Sophie—who grew up in Provence—took one bite and asked if I'd stolen her grandmother's recipe. I hadn't, but I took it as the highest compliment. Since then, it's become my default whenever I want to impress without spending the whole day in the kitchen.

Ingredients

• Yukon Gold or Russet potatoes: Yukon Golds give you a naturally buttery flavor and hold their shape beautifully, while Russets break down just enough to thicken the sauce as it bakes.
• Heavy cream and whole milk: The combination keeps the dish rich without being so heavy you need a nap afterward, and it helps the layers meld together into something silky.
• Gruyere cheese: This is where the nutty, slightly sweet depth comes from, and it melts into the cream like it was always meant to be there.
• Parmesan cheese: A little sharpness to balance the Gruyere, plus it crisps up beautifully on top when the foil comes off.
• Fresh thyme: I learned the hard way that dried thyme doesn't quite cut it here—the fresh leaves release their fragrance into the cream and make the whole dish smell like a French countryside kitchen.
• Garlic and nutmeg: Just enough to add warmth without announcing themselves, they work quietly in the background to round out every bite.
• Yellow onion (optional): I skip it when I want pure potato flavor, but when I add it, the sweetness it brings after baking is worth the extra step.

Instructions

Prep your dish and oven:

Preheat to 180°C (350°F) and generously butter your baking dish so nothing sticks later. Don't skip this step or you'll be scraping burnt cream off the edges for days.

Warm the cream mixture:

Combine cream, milk, garlic, nutmeg, salt, pepper, and thyme in a saucepan over medium heat until it just starts to steam and smell fragrant. Pull it off the heat before it boils, or the dairy can break and turn grainy.

Layer the first half:

Arrange half your potato slices in overlapping rows, scatter over half the onions if using, then sprinkle half the Gruyere and Parmesan. Pour half the warm cream mixture evenly across the top, letting it seep down between the layers.

Repeat and press:

Add the remaining potatoes, onions, cheeses, and cream, then press everything down gently with the back of a spoon to compact the layers and help the liquid distribute.

Top and cover:

Dot the surface with small pieces of butter, add a final handful of Gruyere and a few thyme leaves, then cover tightly with foil. This traps steam and cooks the potatoes through before they brown.

Bake covered, then uncovered:

Bake for 40 minutes under foil, then remove it and bake another 20 minutes until the top is golden and bubbling at the edges. The smell will tell you when it's ready.

Rest before serving:

Let it sit for 10 minutes so the layers set and you don't burn your tongue. Garnish with a few fresh thyme sprigs and serve straight from the dish.

Save

One winter, I made this for my parents' anniversary dinner and forgot to set a timer. I walked back into the kitchen to find the edges deeply caramelized, almost burnt, and thought I'd ruined it. Turns out everyone fought over those crispy corner pieces, and now I intentionally let it go a few minutes longer every time.

Choosing Your Potatoes

Yukon Golds are my go-to because they're creamy and waxy enough to hold their shape, but Russets work if you want the layers to break down a bit more and create an almost mashed-potato-like richness between the slices. I've tried mixing both, and honestly, it's just extra work for no real payoff—pick one and commit.

Make-Ahead and Storage

You can assemble the whole thing up to a day ahead, cover it tightly, and refrigerate until you're ready to bake. Just add an extra 10 minutes to the covered baking time since it'll be starting cold. Leftovers keep for three days in the fridge and reheat beautifully in a low oven, though the top won't be quite as crispy the second time around.

Pairing and Serving Ideas

This gratin is rich enough to stand on its own as a main course if you pair it with a bright, peppery arugula salad, but it also shines alongside roast chicken, seared lamb chops, or even a simple piece of grilled fish. I've served it at both casual weeknight dinners and holiday gatherings, and it always disappears first.

• Top with crispy fried shallots for extra crunch and a hint of sweetness.
• Swap in Emmental or sharp white cheddar if you can't find Gruyere.
• Add a pinch of cayenne to the cream mixture if you like a subtle kick of heat.

Save

Every time I pull this dish out of the oven, I'm reminded that the best recipes aren't always the most complicated—they're the ones that make your kitchen smell like home. I hope this one does the same for you.

Recipe FAQs

→ What type of potatoes work best?

Yukon Gold or Russet potatoes sliced thinly (2–3 mm) provide the ideal texture and flavor for layering.

→ Can I use different cheeses?

Gruyère can be swapped for Emmental or sharp cheddar to vary the richness and taste.

→ How is the thyme incorporated?

Fresh thyme leaves are added to the cream mixture and sprinkled on top for fragrant herb notes.

→ What is the best way to slice potatoes evenly?

Using a mandoline or sharp knife ensures uniformly thin slices, promoting even cooking.

→ How do I achieve a golden, bubbling top?

Baking covered initially locks in moisture, then uncovering allows browning of the cheeses and butter for a crisp finish.

→ Is there a gluten-free option?

Use certified gluten-free cheeses and ingredients to keep the dish gluten-free.